This invention is concerned with colorimetry and more particularly, with apparatus and a process for conducting colorimetric analysis. In accordance with this invention, the analysis of a liquid or colloidal sample can be carried out with greater accuracy than has been possible in the prior art. The preferred aspects of this invention relate to the analysis of water samples in order to accurately determine the concentration of known substances such as the presence of chloride, fluoride ions etceteras. The apparatus and process of this invention uses photoelectric techniques.
Colorimetric analysis of liquid samples has been a part of human technology since prehistory. In this regard, humans have used the color of a solution to determine the concentration of a known substance since man started preparing food. In this regard, humans through their ability to reason, have developed colorimetric analysis as a means of determining the properties of food in relation to a standard usually the personal preferences of an individual. An excellent example of this basic type of colorimetric analysis is the way individuals judge the strength of tea by its color. In this process a given individual develops a standard for his personal preference for tea by comparing his likes to a given color of a tea brew. Hence, the individual has developed a standard. The individual then compares this standard to the color of future tea brews in order to achieve his personal preferences. This mental process is the most basic form of colorimetric analysis. The process of this invention uses state of the art technology to carry out similar analyses to determine its concentration of a wide variety of analytes in solutions as may be contained in various liquids.
In the chemical arts, the term calorimeter refers to an instrument which compares the light transmitted through one solution to the light transmitted through a standard solution. Still another type of colorimeter is an instrument which is capable of measuring directly the amount of light energy which is absorbed by a solution. The first type of instrument is known as a color comparer while the second type is known as a photometer.
The most basic instruments consist of nothing more than a pair of matched tubes wherein one tube contains a standard solution. The more complicated instruments employ photoelectric cells and complex computing and electronic circuits in order to measure transmitted or absorbed light.
Solutions whose concentrations are to be determined by colorimetric techniques using the above described techniques need not be true solutions. The concentrations of colloidal solutions can also be determined by colorimetric technique if they are clear. However, when the solute particles are too large to form true solutions and hence, the solution appears turbid, measurements by true colorimetric techniques can be difficult.
This invention is concerned with an instrument and a related process which is capable of measuring concentrations by classic colorimetric techniques and for determining the relative turbidity of a solution. That is, the instrument and process of this invention is capable of measuring the relative haziness of a solution. More particularly, this invention is concerned with photoelectric apparatus and a related process which is capable of both colorimetric and turbidity analysis.